1. Field of the Invention
The present invention relates to a retainer for accommodating a self-standing packaging bag that can stand by itself in an open state and for supplying such bags to a bag-packing packaging machine.
2. Prior Art
Japanese Patent Application Laid-Open (Kokai) No. S58-73501 discloses one type of a bag-packing packaging machine.
This machine is designed so that packaging bags (which are empty) are accommodated in retainers, and the retainers are continuously conveyed. Various packaging operations such as filling the bags with contents to be packaged and sealing the bag openings, etc. are performed during the conveying process.
Each retainer is provided with a hollow space and a pair of vertical side grooves. The hollow space has a shape that corresponds to the cross-sectional configuration of the body portion of the packaging bag in an open state (i.e., a state in which the opening of the bag is open and the body portion of the bag is inflated), and the pair of vertical side grooves guide the side edges of the packaging bag. The packaging bag in a closed state is put in the hollow space and is opened and filled with the contents by a filling device.
Accordingly, the above-described filling device requires a bag-opening means such as a vacuum suction picker; and as a result, the structure of the device is extremely complicated. Furthermore, the retainer does not have any means for maintaining the opened packaging bag "as is" in its open state. Accordingly, even though the packaging bag once opened has some degree of shape retention if the bag is a self-standing bag, the bag opening tends to close as a result of vibration during the conveying process and of the recovery force of the packaging bag itself. Thus, when the bag is successively filled with liquid and solid substances during the conveyance, it is necessary to install a bag-opening means for each of liquid and solid substances in the filling devices.
Another prior art, Japanese Utility Model Application Laid-Open (Kokai) No. S58-904 discloses that an open self-standing packaging bag (empty bag) is placed in a retainer, the retainer is successively conveyed to a filling station and sealing station, etc., and various packaging operations such as filling of the bag with contents and sealing of the bag opening, etc. are successively performed.
The retainer of this prior art includes a plate which has a retaining hole and insertion grooves. The retaining hole is in a shape that more or less coincides with the cross-sectional shape of the body portion of a self-standing packaging bag of an open state, and the insertion grooves are formed so that both side edges of the packaging bag are inserted and held therein. Thus, in this retainer, the packaging bag of an open state is set in the retaining hole and insertion grooves of the plate. However, there is no clear description about the means that keeps the open state of the bag in this prior art; therefore, it appears that the bag opening cannot be prevented from closing by way of recovery force of the packaging bag.
Still another prior art, Japanese Patent Application Laid-Open (Kokai) No. H10-236448 discloses a retainer that is equipped with a packaging bag retaining means. With this retainer, a packaging bag is held in an open state, and the bag can be reliably positioned at a specified location. However, the structure of the retainer of this prior art is complicated, and the maintenance and cleaning is not accomplished easily.